Sliding failure analysis of a gabion retaining wall at km 31+800 of Lubuk Selasih – Padang city border highway, Indonesia

Abstract

In August 2010, there was a landslide on the down-slope of national road section at Km 31+800 Lubuk Selasih – Padang City Border. In order to prevent further damage, it was necessary to make an immediate repair by constructing a gabion retaining wall. Since this repair was so urgent, physical and mechanical soil parameters for the stability analysis were determined from literature data. The stability analysis considered dangers of overturning, sliding, and soil bearing capacity. For the sliding stability analysis, the value for friction considered only the interaction between the soil and the base of the retaining wall, with the assumption that the contact area was equal to the total area of the entire base of the retaining wall. After the construction was completed, sliding failure occured due to pressure from the backfill embankment. This research performs a reanalysis of the retaining wall stability using soil and gabion parameters determined from field investigation and laboratory testing. In this reanalysis the friction contact area was assumed to be between the soil and the wire mesh of retaining wall. With these parameters and assumption, the main cause of sliding failure became clear, indicating that this approach increased the accuracy of stability analysis for gabion retaining walls.